In a principal aspect, the present invention relates to a light protection apparatus and, more particularly, to a protective element subassembly for use in a light protection apparatus. The light protection apparatus receives light having a harmless component and an intermittent or constant wave harmful component and is constructed to shield the viewer from exposure to the harmful component of the beam of light.
A particular harmful component of light is produced by a laser. Defined as any device that produces or amplifies ultraviolet, visible, or infrared radiation by the process of controlled stimulated emission, the word "laser" is an acronym for Light Amplification by Stimulated Emission of Radiation.
Laser light differs from conventional light in two principal aspects. First, a laser light pulse is substantially monochromatic as contrasted with the normal visible light spectrum which contains a wide variety of wavelengths. Second, a beam of laser light undergoes very little divergence as it emanates from its source. In contrast to most radiation, in which the intensity is proportional to the inverse square of the distance from the point of radiation, the intensity of laser light decreases substantially linearly as a function of distance from the source. Accordingly, laser light can be harmful at far greater distances than conventional light.
In military applications, laser use runs the gamut from blinding devices, directing gunfire, designating targets for laser guided munitions, communications, training aids, fiber optics, scoring systems, landing systems, etc. Thus, a multitude of laser applications exist in a military environment. Hence, laser emissions may be encountered by the combatant, and must be protected against. In contrast, civilian uses of laser light are more controlled. Civilian applications for lasers include welding, cutting, surveying, scanning, communications and medical use.
Because the military laser environment is often not subject to control, protecting against military lasers are extremely difficult. Whether on the battlefield, at sea or in the air, a military combatant must be protected against harmful light.
Light protection apparatus, especially as protection against laser light, are typically provided with filters that attempt to filter the harmful component of a beam of light (laser) from the harmless component of a beam of light (ordinary light). These filter mechanisms suffer the disadvantage that the harmless component of the beam of light is often greatly filtered, often as much as 98% of visible light. Thus, light protection apparatus using filters tend to obscure the user's field of vision. However, the military combatant can ill afford to be burdened with a diminished view of his hostile environment. Also with the advent of the tunable lasers in the battlefield arena, filters alone are insufficient to block the multi frequencies. Thus, filter type light protection apparatus suffer serious drawbacks in military applications.
Accordingly, protection of personnel from laser light is a primary importance. It is advantageous to minimize the amount of non-harmful light screened from the viewer while protecting the viewer from harmful light such as laser. The present invention constitutes an improved light protection apparatus and a protective element subassembly therefore that seeks to overcome the problems discussed while at the same time providing a simple, easily constructed design that is readily adaptable to a variety of light protection needs.